JP4896553B2 - Manufacturing method of microlens array sheet - Google Patents

Description

According to the present invention, a microlens is two-dimensionally arranged on one side of a transparent substrate, and a light transmission opening and a metal light-shielding layer that are accurately positioned on the opposite side of the substrate surface on which the microlens is arranged The present invention relates to a method of manufacturing a microlens array sheet on which a pattern is formed.

In recent years, in displays such as CRTs and PDPs (plasma display panels), electromagnetic waves generated from the front of the display have a negative effect on the human body and malfunction of surrounding electronic devices has become a problem. Along with the clearness of the display, countermeasures against the influence of the display on the surroundings are becoming increasingly important.
In particular, in PDPs where demand is increasing as large thin displays, in addition to electromagnetic wave shielding films, near-infrared absorbing films for preventing malfunctions of various remote control switches using the near-infrared wavelength region, UV light absorbing film used to prevent near-infrared absorbers used in near infrared light absorbing films over time, neon light cut film for adjusting color tone in the visible light region, and external light reflected on the surface of optical filters An antireflection film or the like for preventing this is combined and configured according to the required function.
By using these films as optical filters for displays, measures are taken to improve the image appearance and to reduce the influence on the surroundings.

  On the other hand, various transparent conductive films and electromagnetic wave shielding films have been developed in order to prevent the adverse effect of electromagnetic waves generated from a display on the human body due to leakage to the outside. Known electromagnetic shielding materials can be broadly classified into two types: an electromagnetic shielding material made of a transparent conductive film and an electromagnetic shielding material made of a conductive metal mesh. Among these, the electromagnetic shielding material using a transparent conductive film is superior in transparency to the electromagnetic shielding material using a metal mesh, but has a large surface resistivity and inferior electromagnetic shielding performance. For this reason, in the use which shields the electromagnetic waves from the apparatus which generate | occur | produces strong electromagnetic waves, such as PDP, the electromagnetic wave shielding material by a metal mesh is preferable.

Furthermore, as a manufacturing method of the electromagnetic wave shielding material by an electroconductive metal mesh, the method shown to following (1)-(3) is mentioned.
(1) An etching method in which a metal foil is bonded to a transparent substrate, or a metal thin film is deposited on the transparent substrate, and then a conductive metal pattern is formed by a photolithographic method (see, for example, Patent Document 1).
(2) A printing-plating method in which a conductive metal paste is printed on a transparent substrate and then plated to form a conductive metal pattern (see, for example, Patent Document 2).
(3) A photographic silver-plating method for forming a conductive metal pattern by forming a fine line pattern with developed silver produced by a photographic method and then plating on the developed silver thin film (for example, Patent Document 3 and (See Patent Document 4).

  And, there are two methods shown in the following (a) and (b) for forming a mesh pattern with developed silver produced by a photographic method.

(A) A silver salt-containing layer containing a silver salt provided on a support is exposed and developed to form a metallic silver part and a light-transmitting part, and the metallic silver part is further subjected to physical development and A method of forming a conductive metal part in which conductive metal particles are supported on the metal silver part by plating (see, for example, Patent Document 3). In this method, developed silver does not appear in the portion that is covered with the exposure mask and is not exposed, and developed silver appears in the portion that is not covered with the exposure mask and exposed. Therefore, compared with the exposure mask. This is a negative exposure / development method in which developed silver appears in an inverted form.

(B) A light-sensitive material having a physical development nucleus layer and a silver halide emulsion layer in this order is exposed on a transparent substrate, and metallic silver is deposited on the physical development nucleus in an arbitrary fine line pattern. A method of plating a metal using the physically developed metallic silver as a catalyst nucleus after removing a layer provided on the development nucleus (see, for example, Patent Document 4). In this method, developed silver appears in a portion which is covered with the exposure mask and is not exposed, and developed silver does not appear in a portion which is not covered with the exposure mask and exposed. Is a positive exposure / development method (silver complex diffusion transfer method, hereinafter referred to as DTR method).

  In the present invention, a light-sensitive material of a photographic method applied on the other transparent substrate surface on which no microlens is disposed is irradiated with light from the microlens array surface of the microlens array sheet. A conductive metal light-shielding pattern made of developed silver is formed by exposing developed light to the exposed part of the lens and developing silver on the unexposed part, and a metal plating layer is formed on the conductive metal light-shielding pattern. A positive-type development method is preferably used in which a metal light-shielding layer pattern having a plurality of light-transmitting openings is formed by laminating, and developed silver is developed in a portion that is not exposed.

On the other hand, with respect to the microlens array sheet, light is irradiated from the microlens array surface, and light condensing through the microlens is applied to the opposite surface of the microlens array surface, so that the photocurable resin composition, light shielding properties and light absorption properties are obtained. A microlens array sheet manufacturing method is disclosed in which a shading band pattern is formed by applying a process such as photocuring to the layer having the layers (Patent Documents 5 and 6).
Japanese Patent Laid-Open No. 10-075087 JP 11-170420 A JP 2004-221564 A International Publication No. 2004/007810 Pamphlet JP 2005-134823 A JP 2005-275339 A

When manufacturing the metal mesh pattern of the electromagnetic wave shielding material incorporated in the optical filter, the etching method (1) above leaves only a small part that becomes a thin line part, and most other metals are etched by etching. Dissolving and removing is a problem from the viewpoint of saving resources. Further, the method of depositing a metal thin film has a problem that it cannot be easily manufactured because a huge equipment cost is required.
In the printing-plating method of (2) above, since the conductive paste contains a binder, only a low conductivity can be obtained by printing on the substrate using the conductive paste, and high electromagnetic waves. There was a problem that shield performance could not be obtained.
In the photographic silver-plating method of (3) above, high electromagnetic wave shielding performance is obtained, and there is no restriction on the dimensions of the transparent base material, and it can be produced by roll-to-roll, and the productivity is very high. This is a preferred production method.

On the other hand, in various displays, especially PDPs, an anti-reflection film (AR film) is adopted as the outermost layer as an optical filter to be attached to the display in order to prevent reflection due to external light (outdoor light or indoor illumination light). ing.
In recent years, in various displays, particularly PDPs, there is an increasing demand for viewing images not only in a dark room but also in a state where the room is brightened by illumination or the like. However, when the room is brightened, a phenomenon occurs in which the image becomes white due to reflection or reflection of external light, and the contrast of black and white is further lowered to blur the image.
For this reason, in the PDP, in order to display a clear image without attenuating the emission intensity of the PDP, an optical filter having a high total light transmittance and a small decrease in luminance is required.

However, even with an optical filter using an electromagnetic shielding material with a conductive metal mesh pattern by photographic silver-plating method, the fine line density of the mesh pattern is increased in order to improve electromagnetic shielding properties. However, there is a problem that the total light transmittance is lowered.
In addition, in the conventional microlens array sheets as disclosed in Patent Documents 5 and 6, since the synthetic resin is used for the light shielding band pattern, it does not have conductivity, and the total light beam There has been a problem that it cannot be used as an electromagnetic shielding material having a high transmittance.

  Thus, in the prior art, it can be used as an electromagnetic shielding material having a high total light transmittance, and can also be used for an ordinary transmission screen, and is an inexpensive manufacturing method based on resource saving. The microlens array sheet formed by the above and having a conductive light-shielding band pattern was not provided.

The present invention has been made in view of the above circumstances, and can be used as an electromagnetic wave shielding material having a high total light transmittance, and can also be used for a normal transmission screen. The light-transmitting opening is accurately positioned on the side surface opposite to the substrate surface on which the metal light-shielding layer pattern having conductivity is formed using an inexpensive manufacturing method based on resource saving. and to provide a manufacturing method of the lens array sheet.

In order to solve the above problems, the present invention forms a microlens array surface in which a plurality of circular microlenses are two-dimensionally arranged on one surface of a transparent substrate, and then irradiates light from the microlens array surface. Thus, the photosensitive material of the photographic method applied on the other surface, which is the surface opposite to the microlens array surface of the transparent base material, is collected at the condensing portion of each microlens on the microlens array surface. A light transmission opening having a plurality of circular shapes in the exposed portion by exposing and exposing the exposed photosensitive material using a positive-type silver salt photographic developing method in which developed silver appears in a portion that is not exposed After forming a conductive metal light-shielding pattern made of developed silver and having a two-dimensional arrangement, laminating a metal plating layer by electrolytic plating on the conductive metal light-shielding pattern, Applying a treatment to laminate a blackening treatment layer on the electrolytic plating layer, and forming a metal light shielding layer pattern having a plurality of circular light transmission openings having an electromagnetic wave shielding function. A method for producing a microlens array sheet is provided.
The light irradiation direction for sensitizing the photosensitive material is preferably a direction perpendicular (or substantially perpendicular) to the microlens array surface.
The microlens array surface is preferably formed by forming a microlens array shape pattern by molding using a thermosetting resin or an ultraviolet curable resin on a transparent substrate.

The present invention can be used as an electromagnetic shielding material having a high total light transmittance, and can also be used for a normal transmission screen, on the side opposite to the substrate surface on which the microlens is arranged. In this case, the light transmission opening is accurately positioned so that the portion of the light irradiated from the microlens array surface is the light transmission opening, and is made conductive using an inexpensive manufacturing method based on resource saving. The manufacturing method of the micro lens array sheet in which the metal light shielding layer pattern which has this was formed can be provided.

The microlens array sheet of the present invention has a portion on which light irradiated from the microlens array surface is condensed on the side surface opposite to the substrate surface on which the microlens is arranged (the light converged by the microlens has a light shielding pattern). Since the light transmission opening is accurately positioned so that the cross section passing through the surface matches the light transmission opening, the light collected by the microlens is effectively a gap between the metal light shielding layer patterns. It is possible to pass through the light transmission opening, and the total light transmittance can be increased.
For this reason, when the microlens array sheet of the present invention is used as an electromagnetic shielding material for an optical filter for a display, a fine line of a mesh pattern made of a conductive metal shields light transmission compared to conventional light shielding. The rate can be dramatically increased.

  By using the microlens array sheet of the present invention for a transmissive screen, it becomes possible to effectively and accurately pass the light collected by the microlens through the light transmission opening that is the gap between the metal light shielding layer patterns. A clear image can be obtained.

Hereinafter, the manufacturing method of the microlens array sheet of the present invention will be described in detail based on the best mode.
1A to 1C are schematic cross-sectional views showing a method of forming a conductive metal light-shielding pattern made of developed silver on the opposite side of the microlens array surface of the microlens array sheet in the order of steps. FIG. 2 is a partially cutaway perspective view schematically showing an example of the layer structure shown in FIG. FIG. 3A is a schematic cross-sectional view of the microlens array sheet of the present invention, and FIG. 3B is a partially enlarged view of part A in FIG. FIG. 4 is a partially cutaway perspective view schematically showing the microlens array sheet of the present invention shown in FIG.

  FIG. 5 is a schematic cross-sectional view showing an example of an electromagnetic wave shielding material used for a conventional optical filter for display. An electromagnetic wave shielding material 11 shown in FIG. 5 is formed by forming a light transmission opening 15 and a conductive metal mesh pattern 14 on one surface of a transparent substrate 12. When this electromagnetic shielding material 11 is incorporated in an optical filter for display, an effect of shielding electromagnetic waves can be expected, but the image light from the display has a cross-sectional area of the light transmission opening 15 and the conductive metal pattern 14. Since shielding is performed according to the ratio, there is a problem in that the total light transmittance decreases in inverse proportion to the occupation cross-sectional area ratio of the conductive metal pattern 14.

  Therefore, in the microlens array sheet of the present invention, the portion of the light that is irradiated from the microlens array surface (on the condensing portion of the microlens) is formed on the other surface of the transparent substrate where the microlens is not disposed. A conductive metal light-shielding pattern is provided in which the position) is a light transmission opening and the other part (position not on the light condensing part of the microlens) is a light-shielding part, and further on the light-shielding pattern of the conductive metal A metal plating layer was laminated to form a metal light shielding layer pattern. In other words, the light transmission apertures, which are the gaps between the metal light shielding layer patterns of the electromagnetic wave shielding material, are arranged so as to coincide with the condensing portions of the respective microlenses. As a result, the light having the microlens array surface as the incident side is focused by the microlens before passing through the light transmission opening, so that incident light having a cross-sectional area wider than the opening cross-sectional area of the light transmission opening can be obtained. It is possible to transmit, and the total light transmittance can be increased. In addition, since the external light can be shielded by the light shielding part of the metal light shielding layer pattern, it is possible to prevent the whitening of the image due to the reflection or reflection of the external light, and further the blurring of the image due to the decrease in the monochrome contrast. it can.

FIG. 1 shows a method for manufacturing a light shielding pattern 6 made of conductive metal on a surface 2b opposite to a microlens array surface 2a of a microlens array sheet 1 in the present invention. Is a photosensitive material layer (photographic silver layer) for two-dimensionally arranging microlenses 3a on one surface 2a of the transparent substrate 2 and generating developed silver on the opposite surface 2b of the transparent substrate 2. 4 is formed. In FIG. 1B, the microlens array surface 2a is irradiated with light L from the microlens 3a side, and the light irradiated by the microlens 3a is applied to the photosensitive material layer 4 for exposure. Show. In FIG. 1C, the exposed photosensitive material layer 4 is developed, so that the portion irradiated with the irradiation light condensed by the microlens 3a becomes the light transmission opening 5, and the portion not exposed to the irradiation light is developed silver. This shows that the light shielding pattern 6 of the conductive metal is formed by the developed silver pattern.
As shown in FIG. 1B, the irradiation direction of the light L for sensitizing the photosensitive material layer 4 is preferably a direction perpendicular (or substantially perpendicular) to the microlens array surface 2a. In this case, on the opposite side surface 2b of the microlens array sheet 1 of the present invention, the portion of the light that is irradiated perpendicularly (or substantially perpendicular) to the microlens array surface 2a coincides with the light transmission opening 5. Further, the light transmission opening 5 can be accurately positioned with respect to the microlens 3a to form a light shielding pattern.

  FIG. 2 is a schematic perspective view illustrating the positional relationship between the light shielding pattern 6 of the conductive metal and the microlens 3a under the microlens array sheet 1 in the layer structure shown in FIG. 1C. It is a figure and shows that the light shielding pattern 6 of the conductive metal formed in the surface 2b on the opposite side of the transparent base material 2 has the light transmission opening 5 at a position corresponding to each micro lens 3a. .

FIG. 3 is a schematic cross-sectional view showing an example of the microlens array sheet 1 of the present invention, and a plurality of light beams are formed on the surface 2b of the transparent substrate 2 opposite to the surface 2a on which the microlenses 3a are disposed. A metal light-shielding layer pattern 8 is formed which includes a conductive metal light-shielding pattern 6 having a transmissive opening 5 and a metal plating layer 7 laminated on the conductive metal light-shielding pattern. In the present invention, if necessary, the transparent treatment layer 9 may be provided by applying a transparent resin in order to eliminate irregularities caused by the metal light shielding layer pattern 8. Although FIG. 3 shows an example in which the transparent treatment layer 9 is provided, the transparent treatment layer 9 may be omitted in the present invention.
The transparent resin used for the transparentization treatment layer 9 can be appropriately selected from thermoplastic resins, thermosetting resins, ultraviolet curable resins, electron beam curable resins, ionizing radiation curable resins, and the like, and is particularly limited. is not.

  FIG. 4 is a schematic perspective view showing an example of the layer structure of the microlens array sheet 1 of the present invention. A conductive metal light-shielding pattern 6 having a plurality of light transmission openings 5 adjacent to the transparent substrate 2 supporting the microlens 3a, and a metal laminated on the conductive metal light-shielding pattern 6 A metal light shielding layer pattern 8 made of the plating layer 7 is formed. The transmitted light collected by the microlens 3 a can pass through the plurality of light transmission openings 5 without being blocked by the metal light shielding layer pattern 8. For this reason, when the microlens array sheet 1 of the present invention is incorporated in an optical filter for display as an electromagnetic wave shielding material, the total light transmittance can be improved as compared with a conventional electromagnetic wave shielding material.

(Transparent substrate)
Examples of the transparent material constituting the transparent substrate 2 include a plastic film made of a resin that is transparent in the visible region, has flexibility, and preferably has good heat resistance. Examples of such films include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, triacetyl cellulose, polystyrene, polyolefins, polyurethane resins, Examples thereof include a single layer or a composite film having a thickness of 10 to 600 μm made of polyvinyl chloride, polyimide resin, polyamide resin or the like.

(Formation of microlens array)
The microlens array 3 composed of a plurality of convex microlenses 3a arranged two-dimensionally on one surface 2a of the transparent substrate 2 is obtained by curing an ultraviolet curable resin or an ionizing radiation curable resin using a molding die. It can be formed by molding. The molding die can be manufactured using various processing methods such as precision grinding, electroforming, and laser processing. According to this method, the microlens array 3 made of a reaction cured product of an ultraviolet curable resin or an ionizing radiation curable resin can be manufactured at a low cost. Further, by making the microlens 3a made of resin, the microlens array sheet 1 can be wound around a roll, and the handleability is improved.
The arrangement shape of the microlenses 3a on the microlens array surface 2a is not particularly limited, and any arrangement shape such as a lattice shape or a hexagonal shape (honeycomb shape) can be adopted. The arrangement pitch of the microlenses 3a is preferably 50 to 250 μm.

(Manufacturing method of microlens array sheet)
The back surface 2b of the surface 2a on which the microlens array 3 of the transparent substrate 2 is formed is coated with a positive photosensitive material 4 for photographic production and exposed to irradiation light condensed by the microlens 3a. Developed to form a light shielding pattern 6 made of developed silver. The minimum line width of the light shielding band of the light shielding pattern 6 is preferably 20 to 40 μm. The light-shielding pattern 6 is subjected to metal plating to produce the microlens array sheet of the present invention. The timing of applying the photographic process photosensitive material 4 to the transparent substrate 2 is before the microlenses 3a are formed on the transparent substrate 2, or after the microlenses 3a are formed on the transparent substrate 2. It does not matter.

After forming the microlens array 3 composed of a plurality of microlenses 3a arranged two-dimensionally on the one surface 2a of the transparent substrate 2, a microlens array sheet can be produced by the following general process.
(1) By irradiating light L from the surface 2a on the microlens array 3 side, the photosensitive material 4 of the photographic method applied on the surface 2b opposite to the microlens surface is applied to each microlens 3a. It exposes in a condensing part.
(2) The exposed photosensitive material 4 is developed to form a conductive metal light-shielding pattern 6 made of developed silver produced by a positive development method in which developed silver appears in the unexposed portions. The conductive metal light-shielding pattern 6 has a light transmission opening 5 in the exposed portion.
(3) A metal plating layer 7 is laminated on the conductive metal light shielding pattern 6 to form a metal light shielding layer pattern 8 having a plurality of light transmission openings 5.

(Electromagnetic wave shielding material)
Conventionally, various transparent conductive films and electromagnetic wave shielding films have been developed in response to the requirement that electromagnetic waves generated from a display leak outside and prevent adverse effects on the human body. The publicly known electromagnetic shielding layer is roughly classified into an electromagnetic shielding material made of a transparent conductive film and an electromagnetic shielding material made of a conductive metal mesh. The electromagnetic shielding material using a transparent conductive film is superior in transparency to the electromagnetic shielding material using a metal mesh, but has a large surface resistivity and inferior electromagnetic shielding performance. Since a plasma display generates a large amount of electromagnetic waves, an electromagnetic shielding material made of a metal mesh is preferable.
Furthermore, as a method for producing a conductive metal mesh, a method using a photographic silver-plating method is preferable in that both a high electromagnetic shielding effect and high transparency (high total light transmittance) can be achieved.
The microlens array sheet of the present invention is formed by laminating a metal plating layer 7 on a conductive metal light-shielding pattern 6 produced by a photographic method to increase the thickness and conductivity, thereby making the metal light-shielding layer pattern 8 an electromagnetic wave. It can be used as a shielding material.

(Method for producing metal light-shielding layer pattern)
The manufacturing method of the metal light-shielding layer pattern 8 that can be used as an electromagnetic wave shielding material in the present invention is one of two different silver salt photographic development methods (positive photographic method-plating method, negative photographic method-plating method). A pattern made of developed silver is formed using a positive development method in which developed silver is developed in a portion not exposed to light.

  One method of the silver salt photographic development method is a method (negative type photographic method) carried out using a so-called usual silver salt photographic film that has been known for a long time, for example, the method described in Patent Document 3, that is, A silver salt-containing layer containing a silver salt provided on a support is exposed and developed to form a metallic silver portion and a light transmitting portion, and the metallic silver portion is physically developed and / or plated. It is a method of forming a conductive metal part by carrying conductive metal particles on the metal silver part by processing.

The silver salt photographic development method (positive type photographic production method) used in the present invention is a method described in Patent Document 4, wherein the silver salt photographic development method is applied to dissolve silver halide with a soluble silver complex salt forming agent. In this method, a soluble silver complex salt is formed and simultaneously reduced with a reducing agent (developing agent) such as hydroquinone to deposit metallic silver having an arbitrary fine line pattern on the development nucleus.
In Japanese Examined Patent Publication No. 42-23745, a silver halide emulsion layer and a silver halide solvent (a silver complex salt forming material) are applied, and a conductive film composed of physically developed silver by a silver complex diffusion transfer development method (DTR development method). A technique for forming a conductive layer is described. However, as described above, in order to satisfy simultaneously the translucency of 50% or more of the total light transmittance and the conductivity of 10 ohm / □ or less, which is required for the recent electromagnetic shielding material, the above-mentioned patent publication It was not possible to achieve only with the technique described in.

  Hereinafter, a new method for producing a metal light-shielding layer pattern that can be used as an electromagnetic wave shielding material based on the positive photographic method-plating method used in the present invention will be described.

(Positive photographic process-plating method: physical development nucleus)
It is preferable that a physical development nucleus layer is provided in advance on the transparent substrate on which the developed silver pattern is formed.
As the physical development nuclei, fine particles (having a particle size of about 1 to several tens of nm) made of heavy metals or sulfides thereof are used. Examples thereof include colloids such as gold and silver, metal sulfides obtained by mixing water-soluble salts such as palladium and zinc and sulfides, and the like. The fine particle layer of these physical development nuclei can be provided on the transparent substrate by a vacuum deposition method, a cathode sputtering method, a coating method or the like. From the viewpoint of production efficiency, a coating method is preferably used. The content of physical development nuclei in the physical development nuclei layer is suitably about 0.1 to 10 mg per square meter in solid content.

  The transparent substrate can be provided with an adhesive layer of a polymer latex layer such as vinylidene chloride or polyurethane, and an intermediate layer made of a hydrophilic binder such as gelatin can be provided between the adhesive layer and the physical development nucleus layer. it can.

  The physical development nucleus layer preferably contains a hydrophilic binder. The amount of the hydrophilic binder is preferably about 10 to 300% by mass with respect to the physical development nucleus. As the hydrophilic binder, gelatin, gum arabic, cellulose, albumin, casein, sodium alginate, various starches, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, a copolymer of acrylamide and vinyl imidazole, and the like can be used. The physical development nucleus layer may also contain a hydrophilic binder crosslinking agent.

  The physical development nucleus layer and the intermediate layer can be applied by an application method such as dip coating, slide coating, curtain coating, bar coating, air knife coating, roll coating, gravure coating, spray coating, and the like. In the present invention, the physical development nucleus layer is preferably provided as a continuous and uniform layer by the above-described coating method.

  In the present invention, the supply of silver halide for precipitating metallic silver on the physical development nucleus layer is performed by a method in which the physical development nucleus layer and the silver halide emulsion layer are integrally provided in this order on a transparent substrate, or by another method. There is a method of supplying a soluble silver complex salt from a silver halide emulsion layer provided on a substrate such as paper or a plastic resin film. From the viewpoint of cost and production efficiency, the former physical development nucleus layer and the silver halide emulsion layer are preferably provided integrally.

(Positive photographic process-plating method: silver halide emulsion)
In the present invention, the silver halide emulsion can be produced according to a general method for producing a silver halide emulsion of a silver halide photographic light-sensitive material. The silver halide emulsion is usually prepared by mixing and ripening an aqueous silver nitrate solution, an aqueous halogen solution of sodium chloride or sodium bromide in the presence of gelatin.
The silver halide composition of the silver halide emulsion layer used in the present invention preferably contains 80 mol% or more of silver chloride, and more preferably 90 mol% or more is silver chloride. The conductivity of the physically developed silver formed by increasing the silver chloride content is improved.

  The silver halide emulsion layer used in the present invention is sensitive to various light sources. As one method for producing an electromagnetic wave shielding material, for example, formation of physically developed silver having a fine line pattern such as a mesh shape can be mentioned. In this case, the silver halide emulsion layer is exposed in the form of a fine line pattern. As an exposure method, a method in which a transparent original having a fine line pattern and the silver halide emulsion layer are in close contact with each other and exposed with ultraviolet light, or various laser beams are used. Scanning exposure method. The former contact exposure using ultraviolet light is possible even if the silver halide has relatively low photosensitivity, but in the case of scanning exposure using laser light, relatively high photosensitivity is required. Therefore, when the latter exposure method is used, the silver halide may be subjected to chemical sensitization or spectral sensitization with a sensitizing dye in order to increase the sensitivity of the silver halide. Chemical sensitization includes metal sensitization using a gold compound or silver compound, sulfur sensitization using a sulfur compound, or a combination thereof. Gold-sulfur sensitization using a gold compound and a sulfur compound in combination is preferable. In the exposure method using the laser beam described above, a laser beam having an oscillation wavelength of 450 nm or less, for example, a blue semiconductor laser (also referred to as a violet laser diode) having an oscillation wavelength of 400 to 430 nm is used. It can be handled even under a yellow fluorescent lamp.

  In the present invention, an arbitrary position on the transparent substrate on which the physical development nucleus layer is provided, for example, an adhesive layer, an intermediate layer, a physical development nucleus layer or a silver halide emulsion layer, or a backing layer provided with a support interposed therebetween A dye or pigment for preventing halation or irradiation may be contained.

(Positive photographic process-plating method: exposure and development)
When an electromagnetic wave shielding material is produced using a photosensitive material in which a silver halide emulsion layer is coated directly on the physical development nucleus layer or via an intermediate layer, it is usually an arbitrary one such as a mesh pattern. An exposure mask with a fine line pattern and the photosensitive material are in close contact with each other, or a digital image with an arbitrary fine line pattern is scanned and exposed to the photosensitive material with various laser beam output machines.

  However, in the present invention, instead of using a fine line pattern exposure mask, a microlens array is used. That is, as shown in FIG. 1A, after forming a microlens array 3 composed of a plurality of microlenses 3a arranged two-dimensionally on one side 2a of the transparent substrate 2, as shown in FIG. Further, by irradiating light L from the surface 2a on the microlens array 3 side, the photosensitive material layer 4 applied on the surface 2b opposite to the microlens array surface 2a is applied to each microlens 3a. The light is exposed at the condensing part.

  After performing such exposure processing, silver complex diffusion transfer development (DTR development) occurs by processing in an alkaline solution in the presence of a soluble silver complex salt forming agent and a reducing agent, and silver halide in the unexposed area is changed. It is dissolved to form a silver complex salt, which is reduced on the physical development nuclei to deposit metallic silver, whereby a developed silver pattern 6 can be obtained. The exposed portion is chemically developed in the silver halide emulsion layer to become blackened silver. After the development, the silver halide emulsion layer and the intermediate layer, or the protective layer provided if necessary, are washed away with water, and the developed silver pattern 6 of the unexposed part is exposed on the surface. At the same time, a light transmission opening 5 is formed in the exposed portion.

  After DTR development, the silver halide emulsion layer or the like provided on the physical development nucleus layer may be removed by washing with water or transferring and peeling to a release paper or the like. There are two methods for removing the water washing: a method of removing hot water using a scrubbing roller or the like while jetting it with a nozzle or the like, and a method of removing hot water by jetting with a nozzle or the like.

  Next, a soluble silver complex salt forming agent, a reducing agent, and an alkali solution necessary for silver complex diffusion transfer development will be described. The soluble silver complex salt forming agent is a compound that dissolves silver halide to form a soluble silver complex salt, and the reducing agent is a compound that reduces this soluble silver complex salt to precipitate metallic silver on physical development nuclei. These actions are performed in an alkaline solution.

  Examples of the soluble silver complex forming agent used in the present invention include sodium thiosulfate, thiosulfate such as ammonium thiosulfate, thiocyanate such as sodium thiocyanate and ammonium thiocyanate, alkanolamine, sodium sulfite, and potassium bisulfite. Sulfites such as T. H. Examples include compounds described in 474 to 475 (1977) of James The Theory of the Photographic Process 4th edition.

  As the reducing agent, a developing agent known in the field of photographic development can be used. For example, polyhydroxybenzenes such as hydroquinone, catechol, pyrogallol, methylhydroquinone, chlorohydroquinone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-3-pyrazolidone, 1-phenyl-4-methyl- Examples include 3-pyrazolidones such as 4-hydroxymethyl-3-pyrazolidone, paramethylaminophenol, paraaminophenol, parahydroxyphenylglycine, paraphenylenediamine, and the like.

  The above-mentioned soluble silver complex salt forming agent and reducing agent may be applied to the transparent substrate together with the physical development nucleus layer, added to the silver halide emulsion layer, or contained in the alkaline solution. It may be allowed to be contained, and may be further contained in a plurality of positions, but is preferably contained at least in the alkaline liquid.

  The content of the soluble silver complex salt forming agent in the alkaline solution is suitably used in the range of 0.1 to 5 mol per liter of the developer, and the reducing agent is 0.05 to 1 per liter of the developer. It is suitable to use in the molar range.

  The pH of the alkaline solution is preferably 10 or more, and more preferably in the range of 11-14. Application of the alkaline solution for silver complex diffusion transfer development may be an immersion method or a coating method. The immersion method is, for example, transporting while immersing a transparent substrate provided with a physical development nucleus layer and a silver halide emulsion layer in an alkaline solution stored in a large amount in a tank. For example, about 40 to 120 ml of an alkaline solution per square meter is applied on the silver halide emulsion layer.

(Plating of light-shielding pattern on metallic silver)
The thickness of the metal-plated metal light-shielding layer pattern 8 can be arbitrarily changed according to desired characteristics, but is in the range of 0.5 to 15 μm, preferably 2 to 12 μm.
When the microlens array sheet of the present invention is used as an electromagnetic wave shielding material for an optical filter for display, the metal light shielding layer pattern 8 has a thickness of 0.5 to 15 μm and a minimum line width of a light shielding band of 20 to 40 μm. Shielding of 30 dB or more over a wide frequency band such as 30 MHz to 1,000 MHz with excellent light transmission performance and conductivity performance of total light transmittance of 50% or more and surface resistivity of 10 ohm / □ or less The effect can be demonstrated.

  The metal plating applied to the light-shielding pattern 6 of conductive metal can be any of electroless plating, electrolytic plating, or a combination of both, but a microlens array sheet is produced on the transparent substrate 2. In this case, a microlens array 3 is provided on one surface 2a of the transparent substrate 2, and a roll-like long material in which a photosensitive material layer 4 including a physical development nucleus layer and a silver halide emulsion layer is provided on the opposite surface 2b. From the viewpoint that at least a series of processes of exposure, development process and plating process of the light shielding pattern can be performed on the web, a method in which electroplating or a combination of electroless plating is preferable.

(Plating method)
In the present invention, the method of plating the light shielding pattern 6 made of a conductive metal such as developed silver is as follows.
A light-shielding pattern 6 of developed silver produced by a photographic method is formed on one side of the transparent substrate 2, and copper (Cu) and / or nickel (Ni) is plated on the developed silver layer 6.
In the present invention, the metal plating method can be performed by a known method. For example, the electrolytic plating method is a conventionally known method such as copper, nickel, silver, gold, solder, or a multilayer or composite system of copper / nickel. For these, reference can be made to documents such as “Surface Treatment Technology Overview; Technical Data Center, Inc., December 21, 1987, first edition, pages 281 to 422”.
It is preferable to use copper and / or nickel for reasons such as easy plating, excellent electrical conductivity, plating on a thick film, and low cost.

(Electroless copper plating)
The electroless copper plating solution preferably has a metal copper (Cu) concentration of 0.5 to 10 g / liter, more preferably 2 to 3 g / liter.
As temperature of a plating process liquid, 30-80 degreeC is preferable, More preferably, it is 40-50 degreeC. If the temperature of the plating solution is lower than 30 ° C., the copper deposition rate is slow, and if it is 80 ° C. or higher, the energy cost increases, which is not preferable.
The plating thickness is preferably 0.01 to 1 μm, and more preferably 0.05 to 0.2 μm. Further, the electroless copper plating solution may be any solution as long as it is a known plating solution.

(Electrolytic copper plating)
In the case of electrolytic copper plating, any plating solution such as copper sulfate, copper cyanide, and copper pyrophosphate may be used, but copper sulfate is preferable from the viewpoint of cost. In these electrolytic copper plating solutions, the concentration of copper (Cu) may be set to an appropriate concentration.
When using a copper sulfate plating bath, the sulfuric acid concentration is preferably 20 to 400 g / liter, more preferably 70 to 300 g / liter. If the sulfuric acid concentration is lower than 20 g / liter, the plating solution becomes unstable, and if it is higher than 300 g / liter, abnormalities occur in the plating particles.
The plating temperature is preferably 10 to 60 ° C, more preferably 20 to 40 ° C. If the temperature of the plating solution is lower than 10 ° C., the plating time is increased and the cost is increased, and if it is higher than 60 ° C., the plating appearance is deteriorated.
The current density of electrolytic plating is preferably 0.05 to 20 A / cm ² , more preferably 0.5 to 8 A / cm ² . When the current density of electrolytic plating is lower than 0.05 A / cm ² , the plating time becomes longer and the cost increases. Moreover, when the current density of electrolytic plating is higher than 20 A / cm < ² >, since the external appearance of a plating film will deteriorate, it is unpreferable.

(Electrolytic nickel plating)
When performing electrolytic nickel plating, any plating bath such as Watt bath (nickel sulfate, nickel chloride, boric acid), nickel sulfamate bath (nickel sulfamate, nickel chloride, boric acid), etc. But you can.

(Blackening treatment)
The outermost surface 7a (see FIG. 3B) of the metal plating layer 7 is preferably blackened to prevent reflection of light due to the gloss of the plated metal. As a method of blackening treatment on the surface of nickel plating, there is no particular limitation on the type of blackening treatment film and the composition of the blackening treatment liquid to be used. As a preferable example, when black nickel is used, sulfuric acid of the blackening treatment liquid The concentration is preferably 10 to 50 g / liter, and more preferably 20 to 40 g / liter. When the concentration of nickel sulfate is lower than 10 g / liter, plating deposition is delayed and the cost is increased, and when it is higher than 50 g / liter, the finished color of the blackening treatment is not stable.

(Optical filter manufacturing method)
In the present invention, a light-shielding pattern thin film made of developed silver produced by a photographic process is formed on a transparent substrate using a silver salt photographic development method (positive photographic process-plating process). In addition, a microlens sheet having a metal light-shielding pattern formed by laminating metal layers by plating can be obtained.
The microlens array sheet of the present invention can be used for an optical filter for display as an electromagnetic wave shielding material.
The production method of the optical filter is not particularly limited. For example, an optical filter is produced by laminating an antireflection layer, an electromagnetic wave shielding layer comprising the microlens array sheet of the present invention, a near infrared absorber layer, a neon absorber layer, and the like. can do.

In the microlens array sheet of the present invention, the light transmission opening 5 is formed on the microlens 3a in the metal light-shielding layer pattern 8 formed on the surface 2b opposite to the substrate surface 2a on which the microlens array 3 is arranged. Since it is positioned accurately with respect to each other, it is possible to effectively pass the light collected by each microlens 3a through the light transmission opening 5 which is the gap between the metal light shielding layer patterns 8, and to achieve the total light transmittance. Can be high.
For this reason, when the microlens array sheet of the present invention is used as an electromagnetic shielding material for an optical filter for a display, a fine line of a mesh pattern made of a conductive metal shields light transmission compared to conventional light shielding. The rate can be dramatically increased.

  By using the microlens array sheet of the present invention for a transmission type screen, the light transmission aperture 5 which is a gap between the metal light shielding layer patterns 8 is effectively (accurately) collected from the light collected by each microlens 3a. It is possible to pass through and a clear image can be obtained.

  The microlens array sheet of the present invention can be used as an electromagnetic shielding material for a display optical filter or a transmission screen.

(A)-(c) is typical sectional drawing which shows the method of forming the light-shielding pattern of the electroconductive metal which consists of developed silver in the surface on the opposite side of the micro lens array surface of a micro lens array sheet in order of a process. A partially cutaway perspective view schematically showing an example of the layer structure shown in FIG. 1C, in which a light-shielding pattern of conductive metal made of developed silver is formed on the surface opposite to the microlens array surface of the microlens array sheet. FIG. (A) is typical sectional drawing of the microlens array sheet | seat of this invention, (b) is the elements on larger scale of the A section of (a). It is a partial notch perspective view which shows typically the micro lens array sheet | seat of this invention shown in FIG. It is typical sectional drawing which shows an example of the electromagnetic wave shielding material used for the conventional optical filter for displays.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Micro lens array sheet, 2 ... Transparent base material, 2a ... Micro lens array surface, 2b ... Surface on the opposite side of micro lens array surface, 3 ... Micro lens array, 3a ... Micro lens, 4 ... Photosensitive material layer, 5 DESCRIPTION OF SYMBOLS ... Light transmission opening part, 6 ... Conductive metal light shielding pattern (development silver layer), 7 ... Metal plating layer, 8 ... Metal light shielding layer pattern, 9 ... Transparent treatment layer.

Claims (2)

After forming a microlens array surface in which a plurality of circular microlenses are two-dimensionally arranged on one surface of a transparent substrate, the microlens of the transparent substrate is irradiated with light from the microlens array surface. Photosensitive photosensitive material applied on the other surface, which is the surface opposite to the array surface, is exposed at the condensing portion of each microlens on the microlens array surface, and the exposed photosensitive material is By developing using a positive silver salt photographic developing method in which developed silver is developed in an unexposed portion, a plurality of circular light transmission openings are two-dimensionally arranged in the exposed portion. After creating a light shielding pattern of conductive metal and laminating a metal plating layer by electrolytic plating on the light shielding pattern of conductive metal, blackening treatment is further performed to blacken the electroplating layer. The treated layer is laminated, the manufacturing method of the microlens array sheet and a light transmissive opening that a plurality of circular be having electromagnetic shielding function to form a disposed a metallic light-shielding layer pattern.   2. The microlens array surface is obtained by forming a microlens shape pattern by molding using an ultraviolet curable resin or an ionizing radiation curable resin on a transparent substrate. The manufacturing method of the microlens array sheet | seat described in 1.

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